var book={
	_price:0
};

var attrs={
	get:function(){
		return this._price*1.2;
	},
	set:function(price){
		this._price=price;
	}
};
Object.defineProperty(book,"price",attrs);
book.price=100;
console.log(book.price);

var s=Object.getOwnPropertyDescriptor(book,"price");
console.log(s)
